1. Field of the Invention
The present invention relates generally to the field of ophthalmics, more particularly to ophthalmic devices, still more particularly to ophthalmic devices known as intraocular lenses (IOLs), and even more particularly to iris fixated intraocular lenses and to surgical instruments useful for attaching such lenses to an ocular iris.
2. Background Discussion
At the onset it may helpful to the understanding of the present invention to define the terms xe2x80x9cphakicxe2x80x9d and xe2x80x9caphakicxe2x80x9d as related to human eyes. The term xe2x80x9cphakicxe2x80x9d is applied to an eye in which the natural ocular lens is still present. This is in contrast to an xe2x80x9caphakicxe2x80x9d eye from which the natural ocular lens hasxe2x80x94for any reasonxe2x80x94been removed. A phakic eye is considered a dynamic or active eye because the living natural lens is subject to change over time, while an aphakic eye is considered a static eye because the natural lens has been removed.
Vision in an eye is enabled by light from a viewed image being refracted to the retina by the cornea and the natural lens (and/or any implanted intraocular lens) located posterior of the cornea.
One relatively common ocular problem is impaired or complete loss of vision due to the natural ocular lens becoming cloudy or opaquexe2x80x94a condition known as cataract. The formation of cataracts is typically associated with natural bodily aging, and most individuals over the age of about 60 years suffer from cataracts at least to some extent.
Cataracts cannot currently be cured, reversed, or even significantly arrested. Accordingly, the corrective action involves surgically removing the natural lens when the lens becomes so cloudy that vision is greatly impaired, the result being that a phakic eye becomes an aphakic eye.
After a defective natural lens has been surgically removed, the current vision-restoring practice (since about the 1940""s) is to implant in the aphakic eye an artificial refractive lens called an intraocular lens (IOL) having an optic and optic fixation means. previously, thick, heavy, high diopter spectacles were prescribed for aphakic eyes. Such spectacles however were and still are generally disliked by most patients for their weight and appearance.
Implantable IOLs were initially constructed from rigid polymethyl methacrylate (PMMA) a hard, biocompatable plastic material. More recently, IOLs have been constructed from a soft, elastically deformable, silicone or acrylic material that enables insertion of the IOLs through small ocular incisions.
In addition to the implanting of IOLs in aphakic eyes to restore vision after removal of the natural lens, considerable interest has recently arisen in implanting IOLs in phakic eyes to correct myopia, hyperopia, presbyopia or astigmatism problems associated with non-cataract natural lenses. This implanting of corrective IOLs in phakic eyes is an often-attractive alternative to the wearing of corrective spectacles or contact lenses, which limit certain activities and even certain professions, or having performed such surgical procedures on the cornea as radial keratomy (RK) or photo-radial keratectomy (PRK), which may not be desired by many individuals for various reasons. The implanting of refractive IOLs in phakic eyes to correct vision problems is considered to constitute one of the remaining frontiers of vision correction.
In an aphakic eye, a replacement IOL is now typically implanted in the posterior chamber of the eye from which the natural lens has been removed. In contrast, a corrective IOL for a phakic eye is most desirably implanted in the anterior chamber of the eye, forwardly of the intact natural lens remaining in the posterior chamber of the eye. (In some difficult cases, however, an IOL may be implanted in the anterior chamber after the natural lens has been removed from the posterior chamber.) The former type of IOL is called a posterior chamber IOL and the latter type is called an anterior chamber IOL. There are significant construction differences between these two types of IOLs.
With specific regard to anterior chamber IOLs (with which this application is concerned), there has been recently renewed interest in IOLs constructed for fixation to the iris for correcting vision in phakic eyes (although, some of the earliest IOLs for aphakic eyes were iris fixated anterior chamber IOLs). One reason for renewed interest in iris fixated IOLs for phakic eyes is that fixating (i.e., attaching) the optic supporting structure directly to the iris itself avoids contact by the IOL with the sensitive filtration angle of the eye, thereby reducing subsequent ocular problems.
Iris fixated IOLs are disclosed in recent U.S. Pat. Nos. 4,215,440 and 5,192,319 to Jan Worst. Both of such patents disclose IOLs employing one or more optic fixation members formed having a pair of pincer arms which, by surgical manipulation when attaching the IOLs to an iris, pinch up and hold a small, anterior surface region of the iris in the narrow gap between the pincer arms. This pinching action detachably attaches the IOL to the iris so that the IOL optic is (ideally) fixated in the region of the iris opening (i.e., the pupil of the eye).
However, the present inventor considers that improvements to the iris fixated IOL designs disclosed in the two above-cited Worst patents are desirable. It is, therefore, a principal objective of the present invention to provide such improvements, particularly in the areas of improving optic centration and enabling small incision implanting of iris fixated IOLs.
Moreover, so far as is known to the present inventor, the attaching to the anterior surface of the iris of iris fixated IOLs of the type disclosed by the above-referenced Worst patents has involved a very tedious and difficult two-handed procedure requiring great skill, dexterity, and training.
In this regard, a forceps is used by one of the IOL implanting surgeon""s hand to hold the IOL with the IOL optic centered on the iris. The surgeon uses his other hand to manipulate a needle (called an enclavation needle) to capture and lift a small region of iris stromal tissue adjacent the gap between the pair of pincer arms of one of the IOL fixation members (haptics).
This lifting of iris tissue in the gap region lifts opposing end regions of the pincer arms, thereby causing widening of the gap between the pincer arms. Thus, when the tip of the enclavation needle is withdrawn from the iris tissue, the lifted region of tissue becomes pinched in the narrowing gap between the pincer arms as the arms flex back downwardly to their normal position. This procedure results in the attachment of the related IOL fixation loop to the iris.
As a next step, the forceps and enclavation needle are switched between the surgeon""s hands to perform the same attachment procedure for the second IOL fixation loop to the iris and the resulting attachment of the IOL to the iris.
This two-handed (i.e., bi-manual) IOL-to-iris fixation procedure is not only extremely difficult and very dependant upon the surgeon""s skill, but it does not leave a free hand of the surgeon to perform other, ancillary procedures associated with the surgical implant of the iris fixated IOL.
It is therefore a principal objective of the present invention to provide a combination forceps and enclavation instrument, which enable both the forceps and needle to be operated in a relatively simple manner with one hand. This new combination instrument greatly simplifies the attachment of the above-described types of iris fixated, poster chamber IOLs to an iris and reduces the level of surgical skill required for performing the IOL to-iris attachment procedure.
In accordance with the present invention, there is provided an iris fixated intraocular lens which comprises an optic having an optical axis and anterior and posterior sides and at least two fixation members, and which may have an overall diameter of between about 7.5 mm and about 10 mm. Each of the fixation members have a proximal end region and a distal end region, the proximal end region comprising a flexible strand, preferably, a single flexible strand, fixed to an edge region of the optic so as to extend generally tangentially outwardly therefrom. The distal end region is formed into a loop having defined therein at least one narrow iris pincher gap.
In a preferred embodiment of the invention, the at least one pincher gap is located on a line generally perpendicular to the optical axis, but may alternatively be formed at an angle to the perpendicular line.
It is preferred that the at least two fixation members include first and second fixation members that are substantially identical to one another and are attached to the optic on opposite sides of the optical axis. The first and second fixation members are constructed separately from the optic, the intraocular lens being thereby a three-piece intraocular lens.
It is further preferred that the optic is constructed from an elastically deformable material, which may be a silicone material or an acrylic material. Also, the at least two fixation members lie in an at least substantially common plane located posterior of the optic.
The distal end loop of each of the at least two fixation members may be elongated into a curved shape, and in some embodiments of the invention, each of the distal end loop includes means dividing the loops into first and second segments; in which case, a first pincer gap is defined in the first loop segment and a second pincer gap is defined in the second loop segment. Preferably, the loop dividing means lies generally perpendicular to the optical axis of the optic.
The at least one pincer gap preferably has a width of between about 0.05 mm and about 0.25 mm, and preferably has a length between about 0.2 mm and about 0.5 mm. The pincer gap in the distal end loop of each of the first and second fixation members may be located in a region of the loop closest to said optical axis, or in a region of the loop furthest from said optical axis. In either case, the pincer gaps are spaced a preferred distance between about 8.0 mm and about 9.0 mm away from the optical axis of the optic.
Because the fixation members are constructed as a flexible strand and the optic is constructed from an elastically deformable material, the resulting three-piece iris fixated IOL of the invention can be folded, rolled or otherwise deformed for insertion through a small, sutureless incision in the eye, as is highly desirable for such reasons as minimal patient trauma and the reduced possibility of surgical complications. Also importantly, the flexible strand fixation members enable accurate centration of the associated optic in the patient""s eye upon fixation of the IOL to the iris.
There is additionally provided a combination forceps and enclavation needle instrument, preferably, a hand-held instrument, for use in attaching a fixation loop of an anterior chamber intraocular lens (IOL) to the anterior surface of a human ocular iris, the fixation loop having a narrow iris tissue pincer gap defined therein and having thickened end regions.
The combination instrument comprises a handle portion sized for being held in one hand of a user, the handle having an outer wall and a slender ocular insertion portion having an open distal end, the insertion portion being connected, preferably detachably connected, to the handle portion. The insertion portion is preferably eliptical or oval in transverse cross section with a major cross sectional dimension no greater than about 2.5 mm.
Included in the instrument is a forceps tip projecting from the insertion portion open distal end, the forceps tip having first and second IOL gripping jaws connected for gripping the IOL fixation loop. Preferably, the first forceps tip jaw projects further than said forceps tip second jaw from the insertion portion open distal end. Further included is an enclavation needle tip projecting from the insertion portion open distal end configured for engaging iris tissue and for lifting the engaged iris tissue into the fixation loop pincer gap.
Operating and control means are connected for selectively causing the forceps tip jaws to open and close, for selectively moving the needle tip between a lifted position and a lowered position, and for selectively causing partial rotation of the needle tip in clockwise and counterclockwise directions.
The operating and control means preferably include moving means for moving the forceps tip and needle tip in unison in a selected axial direction.
In a preferred embodiment, the needle tip has an axial helical shape with a sharp distal end and the operating and control means include means for simultaneously moving the needle tip in an axial direction and for rotating the needle tip.
In one version of the combination instrument, the operating and control means include an electric power source, a plurality of reversible electric motors and a plurality of electrical switches connected for providing electrical power to the motors from the power source. Preferably, each of the electrical switches comprises a momentary on-off-momentary on switch having a manually operated portion projecting outwardly from the instrument handle portion. In such case, the manually operated switch portions project outwardly from the handle portion in locations enabling the operation thereof by one hand of an operator holding the handle portion without the necessity of repositioning the hand.
Alternatively, the operating and control means may include a plurality of manually operated thumb wheels that also extend outwardly from the handle portion in locations enabling the operation thereof by one hand of an operator holding the handle portion.
The operating and control means include a first, elongate slender control pin connected to the needle tip and a second, elongate slender control pin pivotally connected to one of the forceps tip jaws, preferably, the second jaw. The operating and control means further include a sleeve slidably disposed around the first control in and a third, elongate slender control pin connected to the sleeve. Means are then provided for pivotally connecting the sleeve to the insertion portion so that axial movement of the third control pin causes the raising or lowering of the sleeve and needle tip.
Further comprising the operating and control means are a first connecting pin detachably connected to the first control pin, a second connecting pin detachably connected to the second control pin and a third connecting pin detachably connected to the third control pin. Also included are respective first, second and third pairs of gears operatively connected to corresponding ones of the first, second and third connecting pins, as well as respective first, second and third reversible electric motors connected to corresponding ones of the first, second and third pairs of gears.
Respective first, second and third thumb wheels mat be connected to corresponding ones of the first, second and third pairs of gears in place of the electric motors.
The combination enclavation needle and forceps instrument of the present inventionxe2x80x94since the dualfunction instrument is configured for one-handed operationxe2x80x94is intended to significantly reduce the level of skill required to fixate an anterior chamber IOL to an anterior surface of an iris over that required when individual enclavation needles and forceps requiring two-handed operation are used, as heretofore has been the case. In addition, and importantly, the combination instrument of the present invention is intended to assure reproducibility of iris fixated IOL fixation procedures.
It may nevertheless sometimes be desirable to provide a generally corresponding single-function instrument having only a needle tip or only a forceps tip because of the easy control provided. In such cases, the associated operating and control means would be limited for operating and controlling to whichever tip is provided.